This invention provides a controllable device for selectively reducing the volume of water discharged by a flush tank. These tanks are commonly associated with toilets, and have a total capacity of anywhere from 21/2 to 9 gallons of water. This quantity is usually discharged at each flushing, in the standard installation. Three considerations have emerged that make it desirable to selectively limit the flushing volume. One of these is the cost of water, and another is the environmental necessity for water conservation. The latter problem is so acute in some areas of the country that laws regulating water consumption have either been passed, or are under consideration. Sewage discharge is another problem. Even heavily diluted sewage is still sewage, and must be handled by processing plants, if it is not to be released where it becomes a health hazard.
Toilet usage involves the disposal of liquid waste about six times as often as it does solid waste. The volume of water required to flush the liquid properly is a small fraction of the quantity required to clear out the solid material. The system must be capable of handling both. Fixed displacement devices, like a masonry brick placed in the flush tank, somewhat reduce the volume, but must be manually removed when a full flush is desired. This is an obvious nuisance. Immersible containers have also been placed in flush tanks, and partition arrangements have been used to divide the tank into compartments having outlet valves that can be selectively operated.
A very practical problem that has limited the acceptance of these arrangements is the requirement for special tank designs, or special actuating mechanisms. Either of these makes it difficult or impractical to incorporate the system into conventional existing installations.